/**
 * @name MarkerClusterer for Google Maps v3
 * @version version 1.0
 * @author Luke Mahe
 * @fileoverview
 * The library creates and manages per-zoom-level clusters for large amounts of
 * markers.
 * <br/>
 * This is a v3 implementation of the
 * <a href="http://gmaps-utility-library-dev.googlecode.com/svn/tags/markerclusterer/"
 * >v2 MarkerClusterer</a>.
 */

/**
 * @license
 * Copyright 2010 Google Inc. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/**
 * A Marker Clusterer that clusters markers.
 *
 * @param {google.maps.Map} map The Google map to attach to.
 * @param {Array.<google.maps.Marker>=} opt_markers Optional markers to add to
 *   the cluster.
 * @param {Object=} opt_options support the following options:
 *     'gridSize': (number) The grid size of a cluster in pixels.
 *     'maxZoom': (number) The maximum zoom level that a marker can be part of a
 *                cluster.
 *     'zoomOnClick': (boolean) Whether the default behaviour of clicking on a
 *                    cluster is to zoom into it.
 *     'averageCenter': (boolean) Whether the center of each cluster should be
 *                      the average of all markers in the cluster.
 *     'minimumClusterSize': (number) The minimum number of markers to be in a
 *                           cluster before the markers are hidden and a count
 *                           is shown.
 *     'styles': (object) An object that has style properties:
 *       'url': (string) The image url.
 *       'height': (number) The image height.
 *       'width': (number) The image width.
 *       'anchor': (Array) The anchor position of the label text.
 *       'textColor': (string) The text color.
 *       'textSize': (number) The text size.
 *       'backgroundPosition': (string) The position of the backgound x, y.
 *       'iconAnchor': (Array) The anchor position of the icon x, y.
 * @constructor
 * @extends google.maps.OverlayView
 */
function MarkerClusterer(map, opt_markers, opt_options) {
	// MarkerClusterer implements google.maps.OverlayView interface. We use the
	// extend function to extend MarkerClusterer with google.maps.OverlayView
	// because it might not always be available when the code is defined so we
	// look for it at the last possible moment. If it doesn't exist now then
	// there is no point going ahead :)
	this.extend(MarkerClusterer, google.maps.OverlayView);
	this.map_ = map;

	/**
   * @type {Array.<google.maps.Marker>}
   * @private
   */
	this.markers_ = [];

	/**
   *  @type {Array.<Cluster>}
   */
	this.clusters_ = [];

	this.sizes = [53, 56, 66, 78, 90];

	/**
   * @private
   */
	this.styles_ = [];

	/**
   * @type {boolean}
   * @private
   */
	this.ready_ = false;

	var options = opt_options || {};

	/**
   * @type {number}
   * @private
   */
	this.gridSize_ = options['gridSize'] || 60;

	/**
   * @private
   */
	this.minClusterSize_ = options['minimumClusterSize'] || 2;

	/**
   * @type {?number}
   * @private
   */
	this.maxZoom_ = options['maxZoom'] || null;

	this.styles_ = options['styles'] || [];

	/**
   * @type {string}
   * @private
   */
	this.imagePath_ = options['imagePath'] || this.MARKER_CLUSTER_IMAGE_PATH_;

	/**
   * @type {string}
   * @private
   */
	this.imageExtension_ = options['imageExtension'] || this.MARKER_CLUSTER_IMAGE_EXTENSION_;

	/**
   * @type {boolean}
   * @private
   */
	this.zoomOnClick_ = true;

	if (options['zoomOnClick'] != undefined) {
		this.zoomOnClick_ = options['zoomOnClick'];
	}

	/**
   * @type {boolean}
   * @private
   */
	this.averageCenter_ = false;

	if (options['averageCenter'] != undefined) {
		this.averageCenter_ = options['averageCenter'];
	}

	this.setupStyles_();

	this.setMap(map);

	/**
   * @type {number}
   * @private
   */
	this.prevZoom_ = this.map_.getZoom();

	// Add the map event listeners
	var that = this;
	google.maps.event.addListener(this.map_, 'zoom_changed',
	function() {
		var zoom = that.map_.getZoom();

		if (that.prevZoom_ != zoom) {
			that.prevZoom_ = zoom;
			that.resetViewport();
		}
	});

	google.maps.event.addListener(this.map_, 'idle',
	function() {
		that.redraw();
	});

	// Finally, add the markers
	if (opt_markers && opt_markers.length) {
		this.addMarkers(opt_markers, false);
	}
}

/**
 * The marker cluster image path.
 *
 * @type {string}
 * @private
 */
MarkerClusterer.prototype.MARKER_CLUSTER_IMAGE_PATH_ = '../images/m';

/**
 * The marker cluster image path.
 *
 * @type {string}
 * @private
 */
MarkerClusterer.prototype.MARKER_CLUSTER_IMAGE_EXTENSION_ = 'png';

/**
 * Extends a objects prototype by anothers.
 *
 * @param {Object} obj1 The object to be extended.
 * @param {Object} obj2 The object to extend with.
 * @return {Object} The new extended object.
 * @ignore
 */
MarkerClusterer.prototype.extend = function(obj1, obj2) {
	return (function(object) {
		for (var property in object.prototype) {
			this.prototype[property] = object.prototype[property];
		}
		return this;
	}).apply(obj1, [obj2]);
};

/**
 * Implementaion of the interface method.
 * @ignore
 */
MarkerClusterer.prototype.onAdd = function() {
	this.setReady_(true);
};

/**
 * Implementaion of the interface method.
 * @ignore
 */
MarkerClusterer.prototype.draw = function() {};

/**
 * Sets up the styles object.
 *
 * @private
 */
MarkerClusterer.prototype.setupStyles_ = function() {
	if (this.styles_.length) {
		return;
	}

	for (var i = 0,
	size; size = this.sizes[i]; i++) {
		this.styles_.push({
			url: this.imagePath_ + (i + 1) + '.' + this.imageExtension_,
			height: size,
			width: size
		});
	}
};

/**
 *  Fit the map to the bounds of the markers in the clusterer.
 */
MarkerClusterer.prototype.fitMapToMarkers = function() {
	var markers = this.getMarkers();
	var bounds = new google.maps.LatLngBounds();
	for (var i = 0,
	marker; marker = markers[i]; i++) {
		bounds.extend(marker.getPosition());
	}

	this.map_.fitBounds(bounds);
};

/**
 *  Sets the styles.
 *
 *  @param {Object} styles The style to set.
 */
MarkerClusterer.prototype.setStyles = function(styles) {
	this.styles_ = styles;
};

/**
 *  Gets the styles.
 *
 *  @return {Object} The styles object.
 */
MarkerClusterer.prototype.getStyles = function() {
	return this.styles_;
};

/**
 * Whether zoom on click is set.
 *
 * @return {boolean} True if zoomOnClick_ is set.
 */
MarkerClusterer.prototype.isZoomOnClick = function() {
	return this.zoomOnClick_;
};

/**
 * Whether average center is set.
 *
 * @return {boolean} True if averageCenter_ is set.
 */
MarkerClusterer.prototype.isAverageCenter = function() {
	return this.averageCenter_;
};

/**
 *  Returns the array of markers in the clusterer.
 *
 *  @return {Array.<google.maps.Marker>} The markers.
 */
MarkerClusterer.prototype.getMarkers = function() {
	return this.markers_;
};

/**
 *  Returns the number of markers in the clusterer
 *
 *  @return {Number} The number of markers.
 */
MarkerClusterer.prototype.getTotalMarkers = function() {
	return this.markers_.length;
};

/**
 *  Sets the max zoom for the clusterer.
 *
 *  @param {number} maxZoom The max zoom level.
 */
MarkerClusterer.prototype.setMaxZoom = function(maxZoom) {
	this.maxZoom_ = maxZoom;
};

/**
 *  Gets the max zoom for the clusterer.
 *
 *  @return {number} The max zoom level.
 */
MarkerClusterer.prototype.getMaxZoom = function() {
	return this.maxZoom_;
};

/**
 *  The function for calculating the cluster icon image.
 *
 *  @param {Array.<google.maps.Marker>} markers The markers in the clusterer.
 *  @param {number} numStyles The number of styles available.
 *  @return {Object} A object properties: 'text' (string) and 'index' (number).
 *  @private
 */
MarkerClusterer.prototype.calculator_ = function(markers, numStyles) {
	var index = 0;
	var count = markers.length;
	var dv = count;
	while (dv !== 0) {
		dv = parseInt(dv / 10, 10);
		index++;
	}

	index = Math.min(index, numStyles);
	return {
		text: count,
		index: index
	};
};

/**
 * Set the calculator function.
 *
 * @param {function(Array, number)} calculator The function to set as the
 *     calculator. The function should return a object properties:
 *     'text' (string) and 'index' (number).
 *
 */
MarkerClusterer.prototype.setCalculator = function(calculator) {
	this.calculator_ = calculator;
};

/**
 * Get the calculator function.
 *
 * @return {function(Array, number)} the calculator function.
 */
MarkerClusterer.prototype.getCalculator = function() {
	return this.calculator_;
};

/**
 * Add an array of markers to the clusterer.
 *
 * @param {Array.<google.maps.Marker>} markers The markers to add.
 * @param {boolean=} opt_nodraw Whether to redraw the clusters.
 */
MarkerClusterer.prototype.addMarkers = function(markers, opt_nodraw) {
	for (var i = 0,
	marker; marker = markers[i]; i++) {
		this.pushMarkerTo_(marker);
	}
	if (!opt_nodraw) {
		this.redraw();
	}
};

/**
 * Pushes a marker to the clusterer.
 *
 * @param {google.maps.Marker} marker The marker to add.
 * @private
 */
MarkerClusterer.prototype.pushMarkerTo_ = function(marker) {
	marker.isAdded = false;
	if (marker['draggable']) {
		// If the marker is draggable add a listener so we update the clusters on
		// the drag end.
		var that = this;
		google.maps.event.addListener(marker, 'dragend',
		function() {
			marker.isAdded = false;
			that.repaint();
		});
	}
	this.markers_.push(marker);
};

/**
 * Adds a marker to the clusterer and redraws if needed.
 *
 * @param {google.maps.Marker} marker The marker to add.
 * @param {boolean=} opt_nodraw Whether to redraw the clusters.
 */
MarkerClusterer.prototype.addMarker = function(marker, opt_nodraw) {
	this.pushMarkerTo_(marker);
	if (!opt_nodraw) {
		this.redraw();
	}
};

/**
 * Removes a marker and returns true if removed, false if not
 *
 * @param {google.maps.Marker} marker The marker to remove
 * @return {boolean} Whether the marker was removed or not
 * @private
 */
MarkerClusterer.prototype.removeMarker_ = function(marker) {
	var index = -1;
	if (this.markers_.indexOf) {
		index = this.markers_.indexOf(marker);
	} else {
		for (var i = 0,
		m; m = this.markers_[i]; i++) {
			if (m == marker) {
				index = i;
				break;
			}
		}
	}

	if (index == -1) {
		// Marker is not in our list of markers.
		return false;
	}

	marker.setMap(null);

	this.markers_.splice(index, 1);

	return true;
};

/**
 * Remove a marker from the cluster.
 *
 * @param {google.maps.Marker} marker The marker to remove.
 * @param {boolean=} opt_nodraw Optional boolean to force no redraw.
 * @return {boolean} True if the marker was removed.
 */
MarkerClusterer.prototype.removeMarker = function(marker, opt_nodraw) {
	var removed = this.removeMarker_(marker);

	if (!opt_nodraw && removed) {
		this.resetViewport();
		this.redraw();
		return true;
	} else {
		return false;
	}
};

/**
 * Removes an array of markers from the cluster.
 *
 * @param {Array.<google.maps.Marker>} markers The markers to remove.
 * @param {boolean=} opt_nodraw Optional boolean to force no redraw.
 */
MarkerClusterer.prototype.removeMarkers = function(markers, opt_nodraw) {
	var removed = false;

	for (var i = 0,
	marker; marker = markers[i]; i++) {
		var r = this.removeMarker_(marker);
		removed = removed || r;
	}

	if (!opt_nodraw && removed) {
		this.resetViewport();
		this.redraw();
		return true;
	}
};

/**
 * Sets the clusterer's ready state.
 *
 * @param {boolean} ready The state.
 * @private
 */
MarkerClusterer.prototype.setReady_ = function(ready) {
	if (!this.ready_) {
		this.ready_ = ready;
		this.createClusters_();
	}
};

/**
 * Returns the number of clusters in the clusterer.
 *
 * @return {number} The number of clusters.
 */
MarkerClusterer.prototype.getTotalClusters = function() {
	return this.clusters_.length;
};

/**
 * Returns the google map that the clusterer is associated with.
 *
 * @return {google.maps.Map} The map.
 */
MarkerClusterer.prototype.getMap = function() {
	return this.map_;
};

/**
 * Sets the google map that the clusterer is associated with.
 *
 * @param {google.maps.Map} map The map.
 */
MarkerClusterer.prototype.setMap = function(map) {
	this.map_ = map;
};

/**
 * Returns the size of the grid.
 *
 * @return {number} The grid size.
 */
MarkerClusterer.prototype.getGridSize = function() {
	return this.gridSize_;
};

/**
 * Sets the size of the grid.
 *
 * @param {number} size The grid size.
 */
MarkerClusterer.prototype.setGridSize = function(size) {
	this.gridSize_ = size;
};

/**
 * Returns the min cluster size.
 *
 * @return {number} The grid size.
 */
MarkerClusterer.prototype.getMinClusterSize = function() {
	return this.minClusterSize_;
};

/**
 * Sets the min cluster size.
 *
 * @param {number} size The grid size.
 */
MarkerClusterer.prototype.setMinClusterSize = function(size) {
	this.minClusterSize_ = size;
};

/**
 * Extends a bounds object by the grid size.
 *
 * @param {google.maps.LatLngBounds} bounds The bounds to extend.
 * @return {google.maps.LatLngBounds} The extended bounds.
 */
MarkerClusterer.prototype.getExtendedBounds = function(bounds) {
	var projection = this.getProjection();

	// Turn the bounds into latlng.
	var tr = new google.maps.LatLng(bounds.getNorthEast().lat(), bounds.getNorthEast().lng());
	var bl = new google.maps.LatLng(bounds.getSouthWest().lat(), bounds.getSouthWest().lng());

	// Convert the points to pixels and the extend out by the grid size.
	var trPix = projection.fromLatLngToDivPixel(tr);
	trPix.x += this.gridSize_;
	trPix.y -= this.gridSize_;

	var blPix = projection.fromLatLngToDivPixel(bl);
	blPix.x -= this.gridSize_;
	blPix.y += this.gridSize_;

	// Convert the pixel points back to LatLng
	var ne = projection.fromDivPixelToLatLng(trPix);
	var sw = projection.fromDivPixelToLatLng(blPix);

	// Extend the bounds to contain the new bounds.
	bounds.extend(ne);
	bounds.extend(sw);

	return bounds;
};

/**
 * Determins if a marker is contained in a bounds.
 *
 * @param {google.maps.Marker} marker The marker to check.
 * @param {google.maps.LatLngBounds} bounds The bounds to check against.
 * @return {boolean} True if the marker is in the bounds.
 * @private
 */
MarkerClusterer.prototype.isMarkerInBounds_ = function(marker, bounds) {
	return bounds.contains(marker.getPosition());
};

/**
 * Clears all clusters and markers from the clusterer.
 */
MarkerClusterer.prototype.clearMarkers = function() {
	this.resetViewport(true);

	// Set the markers a empty array.
	this.markers_ = [];
};

/**
 * Clears all existing clusters and recreates them.
 * @param {boolean} opt_hide To also hide the marker.
 */
MarkerClusterer.prototype.resetViewport = function(opt_hide) {
	// Remove all the clusters
	for (var i = 0,
	cluster; cluster = this.clusters_[i]; i++) {
		cluster.remove();
	}

	// Reset the markers to not be added and to be invisible.
	for (var i = 0,
	marker; marker = this.markers_[i]; i++) {
		marker.isAdded = false;
		if (opt_hide) {
			marker.setMap(null);
		}
	}

	this.clusters_ = [];
};

/**
 *
 */
MarkerClusterer.prototype.repaint = function() {
	var oldClusters = this.clusters_.slice();
	this.clusters_.length = 0;
	this.resetViewport();
	this.redraw();

	// Remove the old clusters.
	// Do it in a timeout so the other clusters have been drawn first.
	window.setTimeout(function() {
		for (var i = 0,
		cluster; cluster = oldClusters[i]; i++) {
			cluster.remove();
		}
	},
	0);
};

/**
 * Redraws the clusters.
 */
MarkerClusterer.prototype.redraw = function() {
	this.createClusters_();
};

/**
 * Calculates the distance between two latlng locations in km.
 * @see http://www.movable-type.co.uk/scripts/latlong.html
 *
 * @param {google.maps.LatLng} p1 The first lat lng point.
 * @param {google.maps.LatLng} p2 The second lat lng point.
 * @return {number} The distance between the two points in km.
 * @private
*/
MarkerClusterer.prototype.distanceBetweenPoints_ = function(p1, p2) {
	if (!p1 || !p2) {
		return 0;
	}

	var R = 6371; // Radius of the Earth in km
	var dLat = (p2.lat() - p1.lat()) * Math.PI / 180;
	var dLon = (p2.lng() - p1.lng()) * Math.PI / 180;
	var a = Math.sin(dLat / 2) * Math.sin(dLat / 2) + Math.cos(p1.lat() * Math.PI / 180) * Math.cos(p2.lat() * Math.PI / 180) * Math.sin(dLon / 2) * Math.sin(dLon / 2);
	var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
	var d = R * c;
	return d;
};

/**
 * Add a marker to a cluster, or creates a new cluster.
 *
 * @param {google.maps.Marker} marker The marker to add.
 * @private
 */
MarkerClusterer.prototype.addToClosestCluster_ = function(marker) {
	var distance = 40000; // Some large number
	var clusterToAddTo = null;
	var pos = marker.getPosition();
	for (var i = 0,
	cluster; cluster = this.clusters_[i]; i++) {
		var center = cluster.getCenter();
		if (center) {
			var d = this.distanceBetweenPoints_(center, marker.getPosition());
			if (d < distance) {
				distance = d;
				clusterToAddTo = cluster;
			}
		}
	}

	if (clusterToAddTo && clusterToAddTo.isMarkerInClusterBounds(marker)) {
		clusterToAddTo.addMarker(marker);
	} else {
		var cluster = new Cluster(this);
		cluster.addMarker(marker);
		this.clusters_.push(cluster);
	}
};

/**
 * Creates the clusters.
 *
 * @private
 */
MarkerClusterer.prototype.createClusters_ = function() {
	if (!this.ready_) {
		return;
	}

	// Get our current map view bounds.
	// Create a new bounds object so we don't affect the map.
	var mapBounds = new google.maps.LatLngBounds(this.map_.getBounds().getSouthWest(), this.map_.getBounds().getNorthEast());
	var bounds = this.getExtendedBounds(mapBounds);

	for (var i = 0,
	marker; marker = this.markers_[i]; i++) {
		if (!marker.isAdded && this.isMarkerInBounds_(marker, bounds)) {
			this.addToClosestCluster_(marker);
		}
	}
};

/**
 * A cluster that contains markers.
 *
 * @param {MarkerClusterer} markerClusterer The markerclusterer that this
 *     cluster is associated with.
 * @constructor
 * @ignore
 */
function Cluster(markerClusterer) {
	this.markerClusterer_ = markerClusterer;
	this.map_ = markerClusterer.getMap();
	this.gridSize_ = markerClusterer.getGridSize();
	this.minClusterSize_ = markerClusterer.getMinClusterSize();
	this.averageCenter_ = markerClusterer.isAverageCenter();
	this.center_ = null;
	this.markers_ = [];
	this.bounds_ = null;
	this.clusterIcon_ = new ClusterIcon(this, markerClusterer.getStyles(), markerClusterer.getGridSize());
}

/**
 * Determins if a marker is already added to the cluster.
 *
 * @param {google.maps.Marker} marker The marker to check.
 * @return {boolean} True if the marker is already added.
 */
Cluster.prototype.isMarkerAlreadyAdded = function(marker) {
	if (this.markers_.indexOf) {
		return this.markers_.indexOf(marker) != -1;
	} else {
		for (var i = 0,
		m; m = this.markers_[i]; i++) {
			if (m == marker) {
				return true;
			}
		}
	}
	return false;
};

/**
 * Add a marker the cluster.
 *
 * @param {google.maps.Marker} marker The marker to add.
 * @return {boolean} True if the marker was added.
 */
Cluster.prototype.addMarker = function(marker) {
	if (this.isMarkerAlreadyAdded(marker)) {
		return false;
	}

	if (!this.center_) {
		this.center_ = marker.getPosition();
		this.calculateBounds_();
	} else {
		if (this.averageCenter_) {
			var l = this.markers_.length + 1;
			var lat = (this.center_.lat() * (l - 1) + marker.getPosition().lat()) / l;
			var lng = (this.center_.lng() * (l - 1) + marker.getPosition().lng()) / l;
			this.center_ = new google.maps.LatLng(lat, lng);
			this.calculateBounds_();
		}
	}

	marker.isAdded = true;
	this.markers_.push(marker);

	var len = this.markers_.length;
	if (len < this.minClusterSize_ && marker.getMap() != this.map_) {
		// Min cluster size not reached so show the marker.
		marker.setMap(this.map_);
	}

	if (len == this.minClusterSize_) {
		// Hide the markers that were showing.
		for (var i = 0; i < len; i++) {
			this.markers_[i].setMap(null);
		}
	}

	if (len >= this.minClusterSize_) {
		marker.setMap(null);
	}

	this.updateIcon();
	return true;
};

/**
 * Returns the marker clusterer that the cluster is associated with.
 *
 * @return {MarkerClusterer} The associated marker clusterer.
 */
Cluster.prototype.getMarkerClusterer = function() {
	return this.markerClusterer_;
};

/**
 * Returns the bounds of the cluster.
 *
 * @return {google.maps.LatLngBounds} the cluster bounds.
 */
Cluster.prototype.getBounds = function() {
	var bounds = new google.maps.LatLngBounds(this.center_, this.center_);
	var markers = this.getMarkers();
	for (var i = 0,
	marker; marker = markers[i]; i++) {
		bounds.extend(marker.getPosition());
	}
	return bounds;
};

/**
 * Removes the cluster
 */
Cluster.prototype.remove = function() {
	this.clusterIcon_.remove();
	this.markers_.length = 0;
	delete this.markers_;
};

/**
 * Returns the center of the cluster.
 *
 * @return {number} The cluster center.
 */
Cluster.prototype.getSize = function() {
	return this.markers_.length;
};

/**
 * Returns the center of the cluster.
 *
 * @return {Array.<google.maps.Marker>} The cluster center.
 */
Cluster.prototype.getMarkers = function() {
	return this.markers_;
};

/**
 * Returns the center of the cluster.
 *
 * @return {google.maps.LatLng} The cluster center.
 */
Cluster.prototype.getCenter = function() {
	return this.center_;
};

/**
 * Calculated the extended bounds of the cluster with the grid.
 *
 * @private
 */
Cluster.prototype.calculateBounds_ = function() {
	var bounds = new google.maps.LatLngBounds(this.center_, this.center_);
	this.bounds_ = this.markerClusterer_.getExtendedBounds(bounds);
};

/**
 * Determines if a marker lies in the clusters bounds.
 *
 * @param {google.maps.Marker} marker The marker to check.
 * @return {boolean} True if the marker lies in the bounds.
 */
Cluster.prototype.isMarkerInClusterBounds = function(marker) {
	return this.bounds_.contains(marker.getPosition());
};

/**
 * Returns the map that the cluster is associated with.
 *
 * @return {google.maps.Map} The map.
 */
Cluster.prototype.getMap = function() {
	return this.map_;
};

/**
 * Updates the cluster icon
 */
Cluster.prototype.updateIcon = function() {
	var zoom = this.map_.getZoom();
	var mz = this.markerClusterer_.getMaxZoom();

	if (mz && zoom > mz) {
		// The zoom is greater than our max zoom so show all the markers in cluster.
		for (var i = 0,
		marker; marker = this.markers_[i]; i++) {
			marker.setMap(this.map_);
		}
		return;
	}

	if (this.markers_.length < this.minClusterSize_) {
		// Min cluster size not yet reached.
		this.clusterIcon_.hide();
		return;
	}

	var numStyles = this.markerClusterer_.getStyles().length;
	var sums = this.markerClusterer_.getCalculator()(this.markers_, numStyles);
	this.clusterIcon_.setCenter(this.center_);
	this.clusterIcon_.setSums(sums);
	this.clusterIcon_.show();
};

/**
 * A cluster icon
 *
 * @param {Cluster} cluster The cluster to be associated with.
 * @param {Object} styles An object that has style properties:
 *     'url': (string) The image url.
 *     'height': (number) The image height.
 *     'width': (number) The image width.
 *     'anchor': (Array) The anchor position of the label text.
 *     'textColor': (string) The text color.
 *     'textSize': (number) The text size.
 *     'backgroundPosition: (string) The background postition x, y.
 * @param {number=} opt_padding Optional padding to apply to the cluster icon.
 * @constructor
 * @extends google.maps.OverlayView
 * @ignore
 */
function ClusterIcon(cluster, styles, opt_padding) {
	cluster.getMarkerClusterer().extend(ClusterIcon, google.maps.OverlayView);

	this.styles_ = styles;
	this.padding_ = opt_padding || 0;
	this.cluster_ = cluster;
	this.center_ = null;
	this.map_ = cluster.getMap();
	this.div_ = null;
	this.sums_ = null;
	this.visible_ = false;

	this.setMap(this.map_);
}

/**
 * Triggers the clusterclick event and zoom's if the option is set.
 *
 * @param {google.maps.MouseEvent} event The event to propagate
 */
ClusterIcon.prototype.triggerClusterClick = function(event) {
	var markerClusterer = this.cluster_.getMarkerClusterer();

	// Trigger the clusterclick event.
	google.maps.event.trigger(markerClusterer, 'clusterclick', this.cluster_, event);

	if (markerClusterer.isZoomOnClick()) {
		// Zoom into the cluster.
		this.map_.fitBounds(this.cluster_.getBounds());
	}
};

/**
 * Adding the cluster icon to the dom.
 * @ignore
 */
ClusterIcon.prototype.onAdd = function() {
	this.div_ = document.createElement('DIV');
	if (this.visible_) {
		var pos = this.getPosFromLatLng_(this.center_);
		this.div_.style.cssText = this.createCss(pos);
		this.div_.innerHTML = this.sums_.text;
	}

	var panes = this.getPanes();
	panes.overlayMouseTarget.appendChild(this.div_);

	var that = this;
	var isDragging = false;
	google.maps.event.addDomListener(this.div_, 'click',
	function(event) {
		// Only perform click when not preceded by a drag
		if (!isDragging) {
			that.triggerClusterClick(event);
		}
	});
	google.maps.event.addDomListener(this.div_, 'mousedown',
	function() {
		isDragging = false;
	});
	google.maps.event.addDomListener(this.div_, 'mousemove',
	function() {
		isDragging = true;
	});
};

/**
 * Returns the position to place the div dending on the latlng.
 *
 * @param {google.maps.LatLng} latlng The position in latlng.
 * @return {google.maps.Point} The position in pixels.
 * @private
 */
ClusterIcon.prototype.getPosFromLatLng_ = function(latlng) {
	var pos = this.getProjection().fromLatLngToDivPixel(latlng);

	if (typeof this.iconAnchor_ === 'object' && this.iconAnchor_.length === 2) {
		pos.x -= this.iconAnchor_[0];
		pos.y -= this.iconAnchor_[1];
	} else {
		pos.x -= parseInt(this.width_ / 2, 10);
		pos.y -= parseInt(this.height_ / 2, 10);
	}
	return pos;
};

/**
 * Draw the icon.
 * @ignore
 */
ClusterIcon.prototype.draw = function() {
	if (this.visible_) {
		var pos = this.getPosFromLatLng_(this.center_);
		this.div_.style.top = pos.y + 'px';
		this.div_.style.left = pos.x + 'px';
	}
};

/**
 * Hide the icon.
 */
ClusterIcon.prototype.hide = function() {
	if (this.div_) {
		this.div_.style.display = 'none';
	}
	this.visible_ = false;
};

/**
 * Position and show the icon.
 */
ClusterIcon.prototype.show = function() {
	if (this.div_) {
		var pos = this.getPosFromLatLng_(this.center_);
		this.div_.style.cssText = this.createCss(pos);
		this.div_.style.display = '';
	}
	this.visible_ = true;
};

/**
 * Remove the icon from the map
 */
ClusterIcon.prototype.remove = function() {
	this.setMap(null);
};

/**
 * Implementation of the onRemove interface.
 * @ignore
 */
ClusterIcon.prototype.onRemove = function() {
	if (this.div_ && this.div_.parentNode) {
		this.hide();
		this.div_.parentNode.removeChild(this.div_);
		this.div_ = null;
	}
};

/**
 * Set the sums of the icon.
 *
 * @param {Object} sums The sums containing:
 *   'text': (string) The text to display in the icon.
 *   'index': (number) The style index of the icon.
 */
ClusterIcon.prototype.setSums = function(sums) {
	this.sums_ = sums;
	this.text_ = sums.text;
	this.index_ = sums.index;
	if (this.div_) {
		this.div_.innerHTML = sums.text;
	}

	this.useStyle();
};

/**
 * Sets the icon to the the styles.
 */
ClusterIcon.prototype.useStyle = function() {
	var index = Math.max(0, this.sums_.index - 1);
	index = Math.min(this.styles_.length - 1, index);
	var style = this.styles_[index];
	this.url_ = style['url'];
	this.height_ = style['height'];
	this.width_ = style['width'];
	this.textColor_ = style['textColor'];
	this.anchor_ = style['anchor'];
	this.textSize_ = style['textSize'];
	this.backgroundPosition_ = style['backgroundPosition'];
	this.iconAnchor_ = style['iconAnchor'];
};

/**
 * Sets the center of the icon.
 *
 * @param {google.maps.LatLng} center The latlng to set as the center.
 */
ClusterIcon.prototype.setCenter = function(center) {
	this.center_ = center;
};

/**
 * Create the css text based on the position of the icon.
 *
 * @param {google.maps.Point} pos The position.
 * @return {string} The css style text.
 */
ClusterIcon.prototype.createCss = function(pos) {
	var style = [];
	style.push('background-image:url(' + this.url_ + ');');
	var backgroundPosition = this.backgroundPosition_ ? this.backgroundPosition_: '0 0';
	style.push('background-position:' + backgroundPosition + ';');

	if (typeof this.anchor_ === 'object') {
		if (typeof this.anchor_[0] === 'number' && this.anchor_[0] > 0 && this.anchor_[0] < this.height_) {
			style.push('height:' + (this.height_ - this.anchor_[0]) + 'px; padding-top:' + this.anchor_[0] + 'px;');
		} else if (typeof this.anchor_[0] === 'number' && this.anchor_[0] < 0 && -this.anchor_[0] < this.height_) {
			style.push('height:' + this.height_ + 'px; line-height:' + (this.height_ + this.anchor_[0]) + 'px;');
		} else {
			style.push('height:' + this.height_ + 'px; line-height:' + this.height_ + 'px;');
		}
		if (typeof this.anchor_[1] === 'number' && this.anchor_[1] > 0 && this.anchor_[1] < this.width_) {
			style.push('width:' + (this.width_ - this.anchor_[1]) + 'px; padding-left:' + this.anchor_[1] + 'px;');
		} else {
			style.push('width:' + this.width_ + 'px; text-align:center;');
		}
	} else {
		style.push('height:' + this.height_ + 'px; line-height:' + this.height_ + 'px; width:' + this.width_ + 'px; text-align:center;');
	}

	var txtColor = this.textColor_ ? this.textColor_: 'black';
	var txtSize = this.textSize_ ? this.textSize_: 11;

	style.push('cursor:pointer; top:' + pos.y + 'px; left:' + pos.x + 'px; color:' + txtColor + '; position:absolute; font-size:' + txtSize + 'px; font-family:Arial,sans-serif; font-weight:bold');
	return style.join('');
};